Motorcycle Repair: 98/99 kawasaki NINJA EX250R NOT STARTING, kawasaki ninja, motorcycle batteries

Question
QUESTION: hello I was wondering if you could help me I have a 1999 kawasaki NINJA EX250R and I just had to replace my motor and swapped it out for a 98 NINJA EX250R the problem I am having is that when I try and start the bike it just turns over and tries to start but back fires and then the battery goes weak the battery is the factory battery I have tried starting fluid spraying it into the airbox but nothing I was told the new motor has 1500 miles on it  and that it was rebuilt and sat as a extra motor for about 2 yrs

ANSWER: Jason, I guess you have to find out of the rebuilt motor was rebuilt correctly. Get ahold of a compression gauge and see what the readings are. Should be about 175, I suppose, on those motors.
There are 250 Ninja forums that might be more helpful, with specific specifications.

Backfiring generally indicates incorrect cam timing, bent valves, major air leaks. If the fuel tank has a vacuum operated petcock, make sure it is functioning properly and that the carbs are getting fuel into the bowls. If you let old gas sit in the carbs, it will separate and that makes it hard to start.

You may have fuel-fouled the spark plugs by now, so take them out, clean the ends and check for a good spark at each one.

If you have low compression readings, then the motor must be removed and the head pulled off to check for valve issues. Determine how to correctly time the camshafts, too, as they might be off a tooth or two.

Bill Silver



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QUESTION: would a bad battery cause this to I tested the battery under load and it was actually saying it had 13.32 volts when it should be 12.8 volts and when tested it said the battery was bad the 13.32 volts was before the load test was started and when the test was finished it said bad battery mind you that the battery is the same battery from 1999 and I am getting a weak blue spark

Answer
Jason, Yikes! Motorcycle batteries, on average, last about 2-4 years. Yours is 12! Time for a new one! When batteries fail, they can hold a "surface charge" but there is little current reserves left and the voltage drops down under load to near nothing.

The ignition system has nothing to do with the battery. CDI ignitions are self-generating, so all you need to do is to get the motor to spin over to generate a spark.

Bill Silver